How do I remove a cloth pinning at some point of the animation?
So it looks impossible to directly animate the Cloth Pinning. The question has been asked here and here, but I'm not sure to understand everyhting.
I've found an other solution, a rather simple one, with the Vertex Weight Mix modifier, but there must be others:

Create your object, give it 2 vertex groups, one for the pinning, the second one must be empty. Give it the Cloth physics.



Create a Force Field &gt; Force next to your object. Animate it: give it Strength of 0 until frame 49 for example, keyframe it at frame 49, at frame 50 give it a Strength of 30.



Give your object a Vertex Weight Mix modifier, put it above the Cloth in the modifiers stack. Choose Vertex Group A &gt; the pinning group, Vertex Group B &gt; the empty group, Mix Set &gt; VGroup A or B. Keyframe the Default Weight A and Default Weight B values: A will be 0 from frame 1 to 49, then 1 at frame 50, B will be 1 from frame 1 to 49, then 0 at frame 50.



It seems to work as planned, from frame 1 to 49, the object collapse with the pinning hanging it, at frame 50 it is blown away by the force field.